Marmion by Sir Walter Scott was published in 1808 and is an epic poem about the Battle of Flodden Field. According to the Edinburgh University Library website, it is about Sir. Marmion and his conquest of Clara de Clare. In order to get rid of her fiance, De Wilton, and marry her, he frames him for treason. However after he frames De Wilton, Marmion dies in the Flodden Field and De Wilton is able to marry Clara instead. Marmion is the poem Gilbert gives to Helen and I think this is significant in perhaps foreshadowing Helen's past and/or the conclusion of the novel. It is already clear that Helen has two love interests, Gilbert and Authur, so it does not seem too far fetched to think that one might either die in pursuit of her or one will try to make the other look bad to win Helen over.
According to the Victorian Era website, books were one of the four presents a woman could take from a man, though it was seen as an intimate thing. I think this is important to note when thinking about Helen and Gilbert's relationship. Helen is apprehensive about taking the book without paying for it at first. But when she does take it, it seems to be a sign that she likes him in some way. I would also like to point out the fact that Gilbert even presents her with this. It is a romantic poem so not only is it making his intentions clear but it is also more than Authur did for her (at least as of chapter 23). This helps to show the different dynamics of Helen's relationships.

Works Cited

"Marmion" Edinburgh University Library, 19 Dec. 2011, http://www.walterscott.lib.ed.ac.uk/works/poetry/marmion.html

"Marmion A Tale of Flodden Field" Project Gutenburg, 14 Oct. 2001, https://www.gutenberg.org/files/4010/4010-h/4010-h.htm

"Victorian Era Courtship Rules and Marriage Facts" Victorian Era: From Georgian to Edwardian, http://victorian-era.org/victorian-era-courtship-rules-and-marriage.html